1. Field of the Invention
The present invention relates to an image forming apparatus such as a recording device, displaying device and the like, wherein an image is formed on a recording medium by electrostatically adhering developer to the recording medium.
2. Related Background Art
Nowadays, various image forming apparatuses in which an image is formed in accordance with image information have been developed and proposed. Some of them utilize powder developer such as toner to form the image by adhering the toner to a recording medium electrostatically.
For example, in a conventional copying machine, the charged photosensitive drum is selectively exposed in accordance with the image information, and the toner is electrostatically adhered to the exposed portion on the drum, thus forming the image.
Recently, as disclosed in the U.S. Pat. No. 3,914,771, toner conveyed by a rotatable magnet is selectively charged by recording electrodes and the charged tone adheres to a recording medium to form an image thereon.
In comparison with the so-called thermal recording technique, such a technique that the toner is electrostatically adhered to the recording medium to form the image thereon has advantages that the recording speed is faster and that the image formed on the photosensitive drum or on the recording medium can be more easily erased and the image can be repeatedly formed.
However, when the toner is wet, the charging ability of the toner is worsened and the fluidity of the toner is reduced, thus often having bad influences upon the image formation.
To avoid this, a technique of providing heating elements to dry the toner contained in a toner container has been proposed; however, this technique has drawback that the whole apparatus is complicated and the number of parts is increased, which makes the apparatus expensive.